AeroTech Open Thread

[StreuB1]

@AeroTech

Is the K76WN-P still available?

If so, have you sold any to dealers recently? Wondering who has any if they are still being produced.

I have an idea.....

 

[StreuB1]

Also, can you stack delay grains and bond the edges and have the faces ignite each other?

Obviously a special forward closure would need to be machined and a one piece insulator would be required so it would fall into the research category. Not concerned with that. Looking for a loooooong smoke trail.

This would be for a 54mm for either the K270W or the K375NW-PS.

 

[Dane Ronnow]

Flew my first K750 today.

Took my 21 pound 4” rocket to 2054 feet. Left the rail with authority!!! Well done Aerotech!!!

Man, thats a great looking rocket.

 

[Theory]

Man, thats a great looking rocket.

thank you my friend!

 

[Rocketjunkie]

Also, can you stack delay grains and bond the edges and have the faces ignite each other?

Obviously a special forward closure would need to be machined and a one piece insulator would be required so it would fall into the research category. Not concerned with that. Looking for a loooooong smoke trail.

This would be for a 54mm for either the K270W or the K375NW-PS.

Use this propellant. It's 40-40 zinc. (Aerotech calls it 8040.) This is the size used in the 54 mm delay grains. https://www.rocketmotorparts.com/29mm_Black_Jack__Propellant_Grain/p1577809_10884768.aspx
Can use https://www.rocketmotorparts.com/Phenolic_Motor_Liner_29mm/p1577809_7796207.aspx std wall
or https://www.rocketmotorparts.com/Phenolic_Motor_Liner_29mm_Thick_Wall/p1577809_20536310.aspx thicker wall for liners.
I have quite a bit of the std wall liner. I make reloads for Aerotech hardware 29-98 mm.
If you are just making smoke trail, my 40-40 zn delay propellant works well and you don't need to vacuum. (PM for more info.) If you are machining your own closures, you can make the delay any size you want. Maybe 54 mm diameter with phenolic liner. (38 mm is used in the 98 mm motors.)

 

[Banzai88]

Lit the business end of a J615 this weekend! Gonna get me some more of these things!

 

[AeroTech]

Flew my first K750 today.

Took my 21 pound 4” rocket to 2054 feet. Left the rail with authority!!! Well done Aerotech!!!

Up close and personal slow motion video:



View attachment 539111

That was gorgeous, thanks!!

 

[AeroTech]

@AeroTech

Is the K76WN-P still available?

If so, have you sold any to dealers recently? Wondering who has any if they are still being produced.

I have an idea.....

We delayed the start of production due to a technical issue with case heating, which we are still working on.

However, we flew a demo motor at BALLS on Sunday in a 3" PML rocket and the flight was incredible. It took off with White Lightning flame, roar and smoke and then shifted into Warp-9 endburner cruise mode during the remaining 17 seconds for a spectacular vertical flight! The spectators applauded!!

 

[AeroTech]

Also, can you stack delay grains and bond the edges and have the faces ignite each other?

Obviously a special forward closure would need to be machined and a one piece insulator would be required so it would fall into the research category. Not concerned with that. Looking for a loooooong smoke trail.

This would be for a 54mm for either the K270W or the K375NW-PS.

That could work but no guarantee. You cannot allow the second and third grain faces to ignite during the motor burn.

 

[AeroTech]

My Hamster Dance 11 rocket, “Eli’s Encore”, left the launch rail at an angle (probably due to the fly-away rail guide), flew significantly down range, and ejected the 24" chute at over 200 feet per second. The shock of the opening broke the eye bolt in the threads and pulled out all the wires from the altimeter. Thanks to Chris Short, we found the rocket but not the nose cone with the electronics inside. It did not qualify under the “must be returned intact to the Event Committee” rule. It flew to at least 20,850 feet.

Specs were:

Diameter: 2.125 inches
Length: 30 inches
Liftoff weight: 3.7 pounds
Propellant weight: 831g
Estimated total impulse: 1,500 N-sec
Estimated burn time: 20 seconds
Estimated altitude: 27,000 feet








Bill Saindon of Balsa Machining was the winner of Hamster Dance 11 with his “Atomizer” rocket powered by a research H13 motor. It flew to approximately 5,800 feet. Bill actually made the only qualified flight of the contest! Bill is also now prefect of Tripoli Gerlach.

Here were all the contestants during the group photo:

 

[Walter Longburn]

Propellant weight: 831g

What type of propellant?

 

[AeroTech]

What type of propellant?

Warp-9

 

[StreuB1]

I am sorry but seeing Gary out in the desert launching rockets with a smile on his face is just the best. Its funny how life comes full circle at times, is it not? He began his career launching rockets in the desert and now look, multi-decades long successful career in aerospace, and still in the desert, launching rockets.

I hope and pray I am allowed to be so unbelievably lucky as well.

 

[StreuB1]

That could work but no guarantee. You cannot allow the second and third grain faces to ignite during the motor burn.

Yep, they would be bonded into the insulator so they would be essentially monolithic. No means for a flame front to bypass the side of the grains and get to the next in line.

 

[StreuB1]

We delayed the start of production due to a technical issue with case heating, which we are still working on.

However, we flew a demo motor at BALLS on Sunday in a 3" PML rocket and the flight was incredible. It took off with White Lightning flame, roar and smoke and then shifted into Warp-9 endburner cruise mode during the remaining 17 seconds for a spectacular vertical flight! The spectators applauded!!

Sounds like its exactly what I am looking for. No rush, I need it in a year. Well, earlier than a year but the flight will be in approximately a year.

Is the data on thrustcurve.org still relatively accurate?

 

[AeroTech]

Sounds like its exactly what I am looking for. No rush, I need it in a year. Well, earlier than a year but the flight will be in approximately a year.

Is the data on thrustcurve.org still relatively accurate?

It will be the same or very close.

 

[markg]

I've got a F22-5J with a date of Sep 01, 2000. The grain is swollen, everything else looks normal. Is this safe to fly if I sand the grain flat? Do I need to replace the delay element?

 

[AeroTech]

I've got a F22-5J with a date of Sep 01, 2000. The grain is swollen, everything else looks normal. Is this safe to fly if I sand the grain flat? Do I need to replace the delay element?
View attachment 539521

It should be OK if the slot isn’t reduced in width. This is Black jack propellant which I’m surprised is swollen as it is stable to moisture. You could sand or slice off the swollen part with a knife. You should not need to replace the delay.

 

[AlexBruccoleri]

Liner question. I received a package for a 98 mm liner and the box was a bit crushed. Visually the liner seems fine. Is it possible the liner could get subtly cracked or are the liners fairly "fine or broken". I.e. when it breaks it shatters.

Thanks, Alex

 

[mikec]

Yesterday, I flew an H550 RMS-EZ that I had gotten years ago by mistake (meant to order the DMS version and then didn't have the forward ring for a long time). It worked perfectly and indeed, the EZ forward closure was easier to deal with. Has AT given up on this approach? I know there were some problems, and customers were not all that enthusiastic, but it seems like a fine idea in theory.

 

[jmasterj]

Yes, RMS-EZ was abandoned.

 

[AeroTech]

Yesterday, I flew an H550 RMS-EZ that I had gotten years ago by mistake (meant to order the DMS version and then didn't have the forward ring for a long time). It worked perfectly and indeed, the EZ forward closure was easier to deal with. Has AT given up on this approach? I know there were some problems, and customers were not all that enthusiastic, but it seems like a fine idea in theory.

We figured out how to make them work reliably (J520W), but did not reintroduce them for the rest of the reloads. There has been some discussion about offering them as a separate product/accessory.

 

[AeroTech]

Liner question. I received a package for a 98 mm liner and the box was a bit crushed. Visually the liner seems fine. Is it possible the liner could get subtly cracked or are the liners fairly "fine or broken". I.e. when it breaks it shatters.

Thanks, Alex

Squeeze the liner on the ends to see if there are any latent cracks. It’s most likely OK.

 

[AlexBruccoleri]

Tight aft closure question. I have an old 54/852 set snd the aft closure is oddly tight. The forward closure fits perfectly into both ends but the aft closure gets snug every 90 degrees or so. I cleaned it thoroughly and I can close it fully with “muscle”.

Is this safe to fly? No apparent damage, just a snug and lopsided tightening experience with nothing installed.

Thanks, Alex

 

[jimzcatz]

yes, of course it is

 

[AlexBruccoleri]

yes, of course it is

Thanks Jim! I will still replace it after this weekend's launch. Threaded joints should be smooth and when they are not, I suspect damage is occurring. Everything looks fine visually though. I just needed to grip the closure with a towel to close it empty.

 

[SolarYellow]

If you have calipers, check the tube and the closure for roundness. Measure across them four ways (every 45 degrees) to see if there is a slight ovalness to the parts. If it got hit hard on one side, that could happen. The forward closure, being round, won't interact with the tightness. The aft closure, being oversize on one axis, will interact with the undersize section of the closure.

Just a hypothesis.

 

[jimzcatz]

If you have calipers, check the tube and the closure for roundness. Measure across them four ways (every 45 degrees) to see if there is a slight ovalness to the parts. If it got hit hard on one side, that could happen. The forward closure, being round, won't interact with the tightness. The aft closure, being oversize on one axis, will interact with the undersize section of the closure.

Just a hypothesis.

This is great advice, I should have thought of it.

 

[AlexBruccoleri]

This is great advice, I should have thought of it.

If you have calipers, check the tube and the closure for roundness. Measure across them four ways (every 45 degrees) to see if there is a slight ovalness to the parts. If it got hit hard on one side, that could happen. The forward closure, being round, won't interact with the tightness. The aft closure, being oversize on one axis, will interact with the undersize section of the closure.

Just a hypothesis.

I had the same thought and my calipers are not with me. My reason for posting was to see if others had seen this issue and flown the hardware without incident or if Aerotech had any comment. I think it will be fine, but if someone on here had a cato with this experience I clearly would not use that closure.

 

[SolarYellow]

My concern would be that if the point where it torques up coincides with a tight point, you don't have enough preload on the threads and aren't compressing the grains adequately. I'm a little bit of a dork on threaded fasteners, but I don't know enough about these motors to know how bad that would be.